This research aims to establish the physical and chemical principles which underlie in the kinetics of the phase transition of polymer gels; phase transitions are a phenomenon universally found in gels where they reversibly swell or shrink in volume by as large as 1000 times in response to changes in temperature, solvent compositions, pH, ionic strength, electric field, or light. The research will examine the time course of the shape, local network density and local strain of gels of various sizes and chemical composition in regards to the kinetic processes of a phase transition. Kinetics of a swelling or shrinking process of a gel with respect to a small change in volume have already been established; it was uniquely characterized by the collective diffusion coefficient of polymer network. Whether or not a similar theory applies to the kinetics of phase transition where the gel volume changes by 3 orders of magnitude is unknown. To examine such a hypothesis and establish the principles of kinetics of phase transition, these viscoelastic quantities will be independently determined within the entire phase diagram of gels. Friction coefficient and shear modulus will be determined by microscopic methods. Dynamic light scattering and fluorescence photobleaching recovery spectroscopy will be used. The mechanism of formation and evolution of patterns that appear in gels undergoing a phase transition will be elucidated so as to formulate the equation of motion that govern the kinetic processes of gels. Finally, it is hoped to clarify the origin of structural inhomogeneities within gels which influence substantially their mechanical, optical, and viscoelastic properties.
